Moderators are being encouraged to document their processes, tools, and guidelines on meta. While we could merely tag everything faq I suspect that it would be better to have a special faq-moderator tag that can only be assigned by the meta moderators to keep everything separate but easily searchable. A user tag would only end up cluttered, so I suggest a nice red tag.
If we have moderator posts that are tagged faq-moderator then it makes it easier for new moderators (pro-tems and newly elected mods) to have a specifically searchable tag rather than having to filter through results for faq and moderator. The former tags should be found by "normal users" looking for FAQ entries, and the later tag should generally pertain to moderator oriented discussions "who's my moderator", or "look what this moderator did" or "when can I be a moderator" (I'm not insinuating those are great questions, just trying to illustrate "moderator" questions that aren't "faq-moderator" questions.)
Additionally, the more "power users" of MSE would be happy to know more about the moderation process and tools, so this would give them a chance to follow specific tags for clarity and openness. A lot of users know a lot about the operation of the Stacks, and so they would have advice to add to the discussion.
There is at present a moderator-faq tag, but it's not red yet.